The blaze, which happened just after 10pm on Tuesday night, has left the River Cottage team at the chef's headquarters in Axminster, Devon, "shocked and upset".

Fearnley-Whittingstall, who is away filming, is yet to find out about the fire, a spokesman said. The cause of the blaze is unknown.

Emergency services, including the police and fire crews, went to the scene after the single-storey building caught fire. Devon and Somerset Fire and Rescue Service said eight fire engines and 80 firefighters attended the farm after receiving calls to a commercial kitchen on fire. The fire was brought under control after nearly three hours and there were no injuries.

A spokesman for River Cottage said: "Late last night a serious fire severely damaged the main barn at River Cottage Park Farm headquarters in Axminster. Thankfully, no people, or animals, were hurt. The River Cottage team are dealing with the damage and are shocked and upset.

"Hugh Fearnley-Whittingstall is away on a long-distance filming trip and will be informed as soon as he can be contacted. The River Cottage team would like to say a big thank you to the fire brigade, who were on the scene quickly and worked hard to contain the fire."

A spokesman for the fire service said: "We received calls to a commercial kitchen on fire. One fire appliance from Colyton and one fire appliance from Axminster attended with Watch Commander Richards in charge.

"Upon arrival, fire crews requested a further three fire appliances from Seaton, Lyme Regis in Dorset, and Honiton; a compressed air foam systems appliance from Chard in Somerset; together with the incident support unit and a supporting appliance from Exmouth and the water bowser from Danes Castle, Exeter.

"A hazardous materials and environmental pollution officer and fire investigation officer was also mobilised to this incident. The single-storey building was well alight, measuring 30 metres by six metres, used as a commercial kitchen."

Members of the Salvation Army also attended the scene to provide catering for those affected by the fire and members of the emergency services. The River Cottage Canteen and Deli at Axminster was unaffected and is open, a spokesman said.

But the cookery school courses at Park Farm will not be running in the short term.

"Anyone booked on a course will be contacted by the River Cottage events team as soon as possible," a spokesman said.

The roof of the cookery school kitchen, in a barn at the farm, has been completely destroyed by the fire, with much of the wood charred and blackened.

Fearnley-Whittingstall, a chef, writer, broadcaster and campaigner, moved into the original River Cottage in Dorset in 1998 to start growing and rearing food of his own.

In 2006 the headquarters moved into the farm near the Devon and Dorset border.

Based in Axminster, it is the base for running courses and events in line with the chef's commitment to ethically-produced food.

Fearnley-Whittingstall gained fame following his River Cottage TV series which led to the publication of The River Cottage Cookbook.